The objectives of this project are to determine the relationship between mesenteric blood flow and intestinal secretion and absorption, and to investigate mechanisms whereby the gastrointestinal hormones secretin, cholecystokinin, gastrin, and glucagon produce their mesenteric vascular effects. Anesthetized cats will be used. Intraluminal perfusion and collection techniques will be used to study intestinal secretory responses, e.g., volume, total protein, enterokinase, and alkaline phosphatase in response to graded hormone infusions and endogenous hormone release. Comparisons will be made between the effects of reduction in arterial inflow produced by camping and by administration of vasoconstrictor drugs on hormone-induced secretory responses. Also, secretory responses will be followed during varied periods of intestinal hypotention. Intestinal absorption will be studied utilizing D-glucose which is actively transported and oleic acid which is passively transported during periods of increased blood flow (induced by gastrointestinal hormones) and decreased blood flow (induced by clamping arterial inflow). Also, with the use of radiolabelled microspheres, the blood flow distribution to intestinal mucosa will be studied when the arterial inflow is reduced by 50 percent to see whether this region of the intestine can autoregulate its blood flow and thereby maintain its secretory and absorptive function. BIBLIOGRAPHIC REFERENCES: Fara, J.W. Mesenteric vasodilator effect of 5-hydroxytryptamine: possible enteric neuron mediation. Arch. Int. Pharmacodyn. 222: 393-407, 1976. Chowdhury, J.R., J.M. Berkowitz, M. Praissman, and J.W. Fara. Effect of sulfated and non-sulfated gastrin and OP-CCK on cat gall bladder in vitro. Experientia, 32: 1173-1174, 1976.